Mauna Loa eruption Day 11: Flow near highway cut off from fresh lava

This story was updated at 10:24 a.m. Dec. 8

Mauna Loa’s volcanic activity changed drastically over the course of Wednesday night, with expert observers reporting fountains of lava reaching unprecedented heights hundreds of feet in the air.

But the towers of fire belie another significant shift on the slopes of one of Earth’s most active volcanoes: The flow front of Fissure 3 is no longer receiving a fresh supply of lava, meaning Daniel K. Inouye Highway (also known as Saddle Road) is no longer under immediate threat of closure.

“We’ve all been focused on the proximity of the dancing lava flows on the saddle towards the Daniel K. Inouye Highway,” U.S. Geology Survey geologist David Phillips told reporters Thursday morning, noting Fissure 3’s flow front remains nearly two miles from the highway spanning the width of Hawai‘i Island.

“Our HVO (Hawaiian Volcano Observatory) field crews have been out since sunup making observations,” Phillips said. “They reported that while the eruption continues out of Fissure 3, the currently active fissure, the supply from Fissure 3 down to the flow front has been cut off.”

Fissure 3’s eruption is no longer feeding the major channel going toward the highway, and appears to be flowing at a reduced rate. This current, “disorganized system” of flows has not coalesced into a new channel, and poses no immediate threat to communities or infrastructure, according to Phillips.

Phillips and fellow USGS geologist Frank Trusdell were unable to conclusively explain Fissure 3’s exceptionally tall fountains, Thursday morning. Possible causes include an increase in the supply rate of volcanic material, or constriction of the lava vent itself.

“Imagine that you’ve got your garden hose, and you put your thumb over the end of the garden hose, and you’re squeezing it out. That’ll make the water come out (more forcefully),” Phillips said.

When asked if local residents and government officials no longer have to worry about threats stemming from Moana Loa, USGS geologist Frank Trusdell advised caution.

“Because the volcano is still erupting, we cannot say that the threat to any of the facilities is done,” he said. “We just have to be vigilant.”

Mayor Mitch Roth and other officials requested visitors to the area act respectfully, noting the Hawai‘i Department of Transportation has prohibited parking on the Mauna Kea access road.

On Friday, groups of cultural practitioners, including the Royal Order of Kamehameha, will be removing debris along the highway from the Mauna Loa access road all the way to Puʻu Huluhulu.

“We are preparing for the arrival of Pele,” said cultural practitioner Noe Noe Wong-Wilson. “It is a practice for many of us to prepare our homes, prepare the areas where we live, and to make sure that these areas are clean (for the Hawaiian goddess).”

The Hawai‘i County Civil Defense Agency is reminding the public all areas adjacent to Daniel K. Inouye Highway, Old Saddle Road, and near the lava flow are closed, as the flow front of Fissure 3 slows.

The flow front of Fissure 3 has slowed and remains 1.75 miles from Daniel K. Inouye Highway, which remains open in both directions. No communities are currently at risk.

Today’s weather forecast calls for 50% chance of rain for the interior areas of Hawai‘i Island, to include Daniel K. Inouye Highway.  A High Wind Warning for North and South Kohala and a Wind Advisory for Hawai‘i Island summits remain in effect.